For more than a century, it has been understood that breast cancers spread from the breast primarily by entering into and passing along lymphatic channels draining the breast. These channels pass into the armpit, into the skin and through the chest wall. Tumor spread is partly impeded by the presence of lymph nodes; in which tumor cells can remain and grow, or pass though and into the blood stream. Near the turn of the century, William Halsted proved the utility of this knowledge by surgically removing all possible lymphatic channels in addition to removing the breast. While this had the disadvantage of being a fairly mutilating procedure, he was able to reduce the rate of local recurrence of breast cancer to six percent from the previously reported recurrence rate of fifty to eighty-five percent when only the breast was removed.
Since the time of Halsted, surgical approaches have moved away from radical techniques toward tissue-sparing approaches. With the ability of earlier detection, minimal surgery; coupled with radiation and/or chemotherapy, has achieved similar results in preventing local recurrence. The problem of detection of tumor spread remains. Often, women who appear to have early stage disease will die of metastatic cancer despite a lack of evidence of spread. Therefore, breast cancer has been called a xe2x80x9csystemic disease.xe2x80x9d This is most likely because cancer cells can spread undetected through lymphatic pathways; often early in the disease.
The primary determinant of survival in breast cancer is the presence or absence of tumor cells within the axillary (armpit) lymph nodes. Axillary nodes are removed to detect tumor spread and prevent recurrence. Tumor spread into other lymphatics that drain the breast is still undetectable, and probably accounts for cases of metastasis when the axillary lymph nodes are free of cancer. Lymphatic flow is determined by pressure and osmolar gradients. Increases in interstitial fluid or in externally applied pressure will enhance lymphatic flow. Entry of tumor cells into lymphatics is an active process of the tumor cells. Once in the lymphatic channels, tumor cells are carried along passively by the flow of lymphatic fluid. Any increase in interstitial fluid or pressure will, therefore, increase the rate of tumor spread.
Breast cancer can recur many years after initial treatment. Presumably, this is because of the undetectable spread of small numbers of tumor cells. While it has been known for many years that cutting into tumors can enhance their spread, present techniques of needle and core biopsies do just this. It has been claimed that these maneuvers don""t spread cancer; however, the truth of these claims might not be apparent for many years.
Presently, the modalities of palpation, x-ray, ultrasound, and MRI are used to detect human breast cancers. Some of these techniques are used also for image-guided biopsy of breast tissue. Mammography is the mainstay of current early detection of breast cancer. This technique requires the forceful compression of the breast between plates to achieve acceptable images. Other known detection techniques, as previously mentioned, include ultrasound, magnetic resonance imaging (hereinafter xe2x80x9cMRIxe2x80x9d), and computerized tomography (hereinafter xe2x80x9cCTxe2x80x9d). Ultrasound images of the breast are obtained using a probe placed directly against the skin of the breast. MRI images are made by placing the breast in a magnetic field, between coils or hanging into a well that is surrounded by a coil. The principles of MRI are known to those of ordinary skill in the art. A description may be found in U.S. Pat. No. 5,437,280 to Hussman entitled xe2x80x9cMagnetic Resonance Breast Localizerxe2x80x9d which is hereby incorporated by reference in its entirety. Stereotactic biopsy techniques are done in a similar fashion; with a patient lying prone, with the breast hanging through a hole in the table. All these methods have shortcomings related to the flaccid nature of the breast which leads to difficulty in manipulating and orienting the organ. Additionally, some of these methods are very uncomfortable for the patient. The pain often associated with the forceful compression of the breast between plates in mammography being a prime example.
Early detection of breast cancers has spurred increasing interest in early intervention. Open biopsy techniques have given way to more image-guided biopsy methods which currently require forceful compression of the breast for stabilization, and require the forceful passage of instruments into the breast which often cause considerable bleeding; especially once the compression has been released. The tissue is in a distorted state and accurate removal of a specific volume of breast tissue is difficult. Present techniques for image-guided biopsy of the breast are limited by the size of the lesion to be removed, and by continuing challenges of bleeding and spread of tumor cells. Removal of lesions greater than a centimeter is generally not possible by these methods.
One object of the present invention is to allow for improved imaging and intervention in diagnosis and treatment of cancer, particularly early stage human breast cancer. Another object of the present invention is to allow for the accurate removal of tissue in a minimally bleeding or bloodless field.
One embodiment of the invention is a fixation apparatus for a breast comprising a cup-like body having a side wall with an open top end and an open bottom end and a fluid evacuation duct. The body defines a chamber adapted to receive a portion of the breast. A gasket is attached to the bottom end and is adapted to provide a substantially fluid tight seal between the body and an area of skin around the breast. A suction ring is attached to the top end and is adapted to provide a substantially fluid tight seal between the body and a second area on the breast. The apparatus may further include a hose attached to the fluid evacuation duct and connected to a pump capable of evacuating fluid in the cup-like body and mounted on the breast such that the gasket and suction ring provide a substantially fluid tight seal between the body and the first and second areas.
Another embodiment of the present invention is also a fixation apparatus for a protuberance of a body that comprises a cup-like body having a continuous wall and a port. The wall is open at one end and the wall defines a volume adapted to receive the protuberance without the protuberance contacting the wall. A gasket is attached to and adapted to provide a substantially fluid tight seal between the body and an area of skin around the protuberance. The fixation apparatus may further include a tubular member connecting the port to a pump for removing fluid to create a reduced or negative pressure within the volume and a pressure gauge connected to the fixation apparatus to monitor the pressure in the cup-like body.
Another embodiment of the present invention is a minimally invasive tissue saw. The tissue saw comprises a shaft extending along a first axis between a proximal end and a distal end and has a first cross section at the distal end. The tissue saw has a cutting head extending between a connecting end and a cutting end. The connecting end is pivotally connected to the distal end of the shaft so that at least a portion of the cutting head is able to swivel back and forth substantially along a second axis, the second axis in a direction transverse to the first axis. The cutting head has a cutting surface at the cutting end and extends across a width in the second axis and is able to swivel back and forth to cut a slit in tissue. The slit has a second cross section with the cutting head having at least one insertion surface substantially adjacent the cutting surface. The insertion surface extends between the connecting end and the cutting end and tapers from the first cross section at the connecting end to the second cross section at the cutting end. A portion of the insertion surface is a cauterizing element and extends around a strip of the insertion surface for cauterizing the tissue surrounding the slit.
In yet another embodiment the present invention is a minimally invasive device for removing a specimen of tissue with a cylinder extending along and rotatable around a first axis defined between a proximal end and a distal end. The cylinder has an interior surface and an exterior surface with a plurality of cutting arms. Each arm has an inner surface and an outer surface with the surfaces extending between a forward edge and a trailing edge. A portion of the forward edge defines a cutting edge and the cutting edge extends past the distal end of the cylinder to cut tissue. The arms are pivotally connected to the cylinder at the distal end and pivot between an open position and a closed position. The inner surface of each arm is adjacent to and substantially overlaps the exterior surface of the cylinder in the open position. A portion of the inner surface of each arm extends beyond the distal end of the cylinder and is adjacent tissue in the closed position.
Another embodiment of the invention is a minimally invasive tissue biopsy device comprising a cannula having a proximal end and a distal end and a first longitudinal axis defined between the ends. The device also includes a means for cutting a slit in tissue with the slit being in a second axis substantially transverse to the first longitudinal axis. The device further includes a trailing means for cauterizing substantially all of the tissue surrounding the slit.
Another embodiment of the invention is a method comprising: providing a retaining sleeve and a tissue saw. The retaining sleeve has a proximal and a distal end with the retaining sleeve having a first cross-section at the distal end. The tissue saw has an oscillating cutting head and a trailing coagulating element. The head has a cutting edge and a tapering insertion surface for advancing the retaining sleeve and the tissue saw along a first axis toward a lesion while the cutting edge oscillates back and forth and cuts an entry wound in tissue. The entry wound is a substantially linear slit having a second cross-section. The entry wound is distorted from the second cross-section of the slit to the first cross-section of the retaining sleeve. The tissue surrounding the slit is cauterized with the trailing coagulating element. The cauterization occurs as the tissue saw and retaining sleeve are advanced toward the lesion.